It may not be enough. 45W @ 12V = 3.75a (W/V=A) Using the Casetronics PS as an example, it needs ~5a @ 12V, which is 60W. You'll need to add up the draw of each of your components (everything should have a label with this info on it, with the exception of the motherboard.) The USB touchscreen may also have an option for external power, which would reduce the load on this PS. If not, you can also look at using a self powered (rather than bus powered) USB hub.

Looking at those Targus PSU/bricks, one of those would be perfect to power a iWill ZPC. Might post this combo in general hardware. Everyone is fixated with Epia based systems and the PW boards ATM (understandabley) and seem to be missing alternatives. this would of course need a VGA screen, so we would need Armen to get that VGA motorised Touch screen into the market place.